There are different types of tools for controllably treating one or more wafer workpieces such as silicon wafers used in semiconductor circuit fabrication. As an illustrative example, ion implanters selective dope silicon wafers by bombarding them with ions of a controlled concentration.
Such processing tools include robots for moving wafers along controlled travel paths from one workstation to a next workstation until all processing steps have been performed. In the illustrative example, an ion implanter includes a robot that moves untreated wafers from a cassette storage device to a load lock through which the wafer is inserted into a low pressure implantation chamber where it is grasped and manipulated by another robot. These robots have movable arms that grip the wafer and release the wafer once it has been delivered to a desired position/orientation.
When a wafer engages a support such as a robot gripper mechanism sometimes referred to as a chuck, particles are generated as a result of the clamping chuck impacting the wafer's edge and from the wafer's edge sliding along the clamp chuck contact surface caused by slight chuck to wafer misalignments. Particle generation increases as the impact force increases and as the degree of misalignment increases.
After the wafer is chucked, additional particles can be generated from the wafer shifting within the chuck. This is caused by the wafer transfer mechanisms clamping force deflecting the gripper arms and chucks. As a result, the position and angle of the clamping chuck relative to the wafer changes causing the wafer to shift within the chuck. This deflection also results in wafer position errors during wafer treatment by the tool.